Abrading apparatus



June 7, 1938. H-. w. DEMPSEY "ABR'ADING APPARATUS Filed March 8, 1937 2 Sheets- Sheet 1 mvszvroa HARRY woewsev BYZ ATTORNEYS June 7', 1938. H. w. DEMPSEY ABRADING APPARATUS Filed March 8, 1937 2 Sheets-Sheet 2 9 2 /z7////r// ///V//////// iii 3 v.4

IWENTOR HARRY VLDEMPSEIYJ I ATTORNEYS Patented June 7, 1938 UNITED STATES ABRADING APPARATUS Harry W. Dempsey, Charlotte, Mich.

Application March 8,

8 Claims.

This invention relates generally to abrading apparatus and refers more particularly to improvements in machine operated abrading apparatus. I

One of the essential objects of the invention is .to provide an apparatus of this type that is capable of abrading the work uniformly and at a higher rate of speed than heretofore. Preferably, the apparatus is sufliciently flexible to enable the abrading element to follow the contour of the work, and is soft enough so the abrading element will not gouge into the work.

'Another object is to improve the means for attaching the abrading element-to the body of the apparatus so that the entire working surface of the abrading element will be free of fastening I means, such as screws and the like for proper engagement with the work. Such construction thereby eliminates the possibility of screws or I 20 other fastening means used in the past at the center of the abrading element from gouging into the Work. In other words, my abrading apparatus has a yielding working surface without screws or other fastening elements at the center thereof.

Another object is to provide an abrading apparatus that is adaptable to any surface and any material that is unfinished, finished, or painted.

Such apparatus can be used for polishing or other purposes by replacing the sheet of sandpaper with a layer of felt, sheepskin, canvas, etc., and is so constructed that it can be used while the rotary portion is in motion for block sanding surfaces. Actually a true surface to surface contact is obtained. U

The foregoing, as well as other objects, will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:-

Figure 1 is a side elevation of apparatus embodying my invention with parts broken away and in section;

Figure 2 is a top plan view of the abrading element upon the rotary body; v

Figure 8 is a plan view of the abrading element.

55 Referring to the drawings,A is the rotary body, B is the abrading element, and C is the filler pad of an abrading apparatus embodying my inven-' tion.

Preferably. the rotary body A comprises two in complementary pads or sections I and 2, respec- 1937, Serial No. 129,737

PATENT OFFICE tively, and is preferably mounted upon a stub shaft 3 which may be a part of any suitable drive mechanism. ,Preferably, the stub shaft 3 is journalled in a gear box 4 and is driven by beveled gears 5 and 6, respectively, from a suitable drive shaft 1. As shown, this stub shaft 3 is tubular and contains a tube 8 for water. Any suitable conduit, such as 9, controlled by a valve I0 may be employed for supplying water to'the tube 8.

'In the present instance, the, section I constitutes the working pad, while the section 2 0011-, stitutes the backing pad. Preferably, the outer face I I of the Working pad is slightly concave and is provided at the center thereof with a circular recess I2. The rear face I3 of the working pad I is substantially flat and is provided adjacent the outer edges thereof with a series of circular re- 'cesses I4 and a series of laterally projecting pins the working pad I is a circular hole ll, while arranged in a circle just inside and concentric with the circle of recesses I4 are a series of holes I9. The base of the pad I is preferably relatively hard and comprises acomposition of rubber and fabric, while the superstructure 2I onsaid baseis preferably formed of pure gum rubber only. Thus, the holes I! and I9 and the recesses I4 tend to lighten the pad I. The recesses l4 enhance the flexibility of the pad at its outer edges and thereby eliminate the possibility of the pad leaving marks upon, or otherwise damaging the work. In this "connection, it should be noted that the arrangement of recesses ll issuch that alternate hard and soft'spots 22 and 2!, respectively, are provided in the outer surface II of the pad at the outer edges thereof, the hard spots 22 extending radially and forming in effect ribs to cooperate with the abrading element B for sanding purposes. and the soft spots 23 to assist in the finishing operations. the backing pad 2 is preferably fiat and is provided' at the center thereof with a circular recess 25 for receiving the 'inner end So of the stub shaft 3. The inner face. 26 of the backing pad 2 is substantially flat and is offset relative to the edges 21 of the .pad. Preferably, there is an annular groove 28 in the inner face of the pad 2 adjacent the edges 21 thereof for receiving the outer wall ,29 of this groove is inclined and ex- The outer face 24 of tends to said edges 21. There are also circular 1 recesses 30 and 3| respectively arr'anged'in circles concentric with the recess 25 to lighten the l 56 pins l5 projecting from the working pad I. The

pa d. At the center of the pad 2 is a circular hole 32 that is adapted to register with the hole I1 in the working pad. The base 33 of the backing pad 2 is preferably relatively hard and comprises a composition of rubber and fabric, while the superstructure 34 on said base is preferably formed of pure gum rubber only. Thus, the backing pad 2 will reinforce the working pad I and will make the latter strong enough to apply the proper pressure for abrading purposes. Moreover, the backing pad 2 protects the operator from the pins I5 constituting the attaching means for the abrading element B.

The abrading element B preferably comprises a sheet of sandpaper having a hole 35 therein at the center thereof for registration with the holes I! and 32, respectively, in the pads I and 2, and is provided at its outer edges with a series of radially extending tabs 35 having apertures 36 therein for engagement with the pins I5. Thus, the means for attaching the abrading element B to the body A are between the sections I and 2 of the body adjacent the periphery thereof, instead of at the center as heretofore. The filler pad C is preferably located between the abrading element B and the working pad I and is equal in area to the area of the working pad. As shown, this filler pad C is formed of sponge rubber and forms a yieldable cushion for the abrading element B. The outer face 31 of the filler pad C is normally convex, but is adapted to flatten out to insure an even abrading action when the apparatus is in use. The inner face 38 of the filler pad is slightly convex at the center thereof for engagement with the concave outer face of the working pad and has a circular boss .or pilot 39 at the center thereof for engagement.

with the central recess I2 in the outer face of the working pad. Thus, due to this central arrangement of the recess I2 and pilot 39, the filler pad C will not throw itself ofl center during rotation of the body A. The filler pad C is also provided with a central hole 40 for registration with the holes I1, 32, and 34', respectively, in the sections I and 2 of the body and in the abrading element B. If desired, the filler pad C may be formed of felt, or some other soft material, as

' long as it forms a proper yielding cushion for the abrading element.

To assemble the parts for use, an abrading element, such as a sheet B of sandpaper, may be,

placed over the outer face of the filler pad C, and the tabs 35 may be extended around the edges ii of the working pad I into engagement with the pins I5. The working pad I may then be assembled with the backing pad 2 upon the stub shaft 3, as illustrated in Figure 1. *In this connection, it will be observed by reference to Figure 1 that the body A is held upon the stub shaft 3 by'means of a flanged screw and a flange 5| on the stub shaft. Preferably, the screw '50 extends through the holes I1 and 32 and the body sections I and 2 and threadedly engages a socket 52 in the end of the stub shaft 3. The flange 53 is received in the recess I2 in the working pad and is concealed by the filler pad C. Preferably, this flange 53 bears against the bottom wall of the recess I2,

while the flange 5| of the stub shaft bears against the flat rear wall of the backing pad 2. 54 is a polygonal portion of thestub shaft simulating a nut, and 55 is a polygonal socket in the end of the screw 50 for receiving asuitable tool to facilitate the connection between the parts. 58 is a passage in the screw 50 for conducting water from thetube 3 to the registering openings 40 and II in the filler pad C and abrading element B.

What I claim as my invention is:

1. In a device of the class described, a rotary body having a working pad and a backing pad, a cushion on the working face of the workinfl pad, and an abrading element upon the cushion and having attaching means anchored between the pads aforesaid.

'2. In a device of the character described, a

. worldng pad provided in its front face with an enlarged recess, a filler pad of resilient material,

an enlarged boss on the rear face of said flller pad engaging said recess and positioning said filler pad relative to said working pad, said filler pad, including said boss, being formed entirely of resilient material.

3. In a device of the character described, a

working pad having an enlarged recess in its front face, a filler pad of resilient material, an enlarged bosson the rear face of said filler pad engaging said recess and positioning said filler pad relative to said working pad, said iiller pad, including said boss, being entirely formed of resilient material, and said working pad having a relatively rigid rear face, and having a forward face of resilient material.

- 4. In a device of the character described, a working pad having an enlarged recess formed in its front face, a filler pad of resilient material, an enlarged boss on the rear face of said filler pad engaging said recess and positioning said filler pad relative to said working pad, said working pad having aplurality of apertures therethrough.

5. In a device ofthe character described, a

working pad, an enlarged recess formed in the front face of said working pad, a filler padof resilient material, an enlarged boss on the rear face of said'flller pad engaging said recess and pad engaging said recess and positioning said flller pad relative to said working pad, -a plurality of pins extending rearwardly from the rear surface of said working pad, abrading sheet material arranged over said flller pad and having peripheral apertures engaging said pins, and a backing pad engaging the rear surface of said working pad and having a circumferential groove in its forward face receiving said pins.

7. In a device of the character described, an abrading element having alternate layers from front to back of resilient and of relatively rigid material, and havingrecesses in said layers to reduce the weight of said element and to provide alternate hard and soft spots on the working surface.

8. In a device of the class described, a rotary body having a working pad and a backing pad,

the base of each pad comprising a relatively hard composition of rubber and fabric, the superstructure of each pad comprising relatively soft pure gum rubber, the base of the working pad having holes arranged in substantially concentric circles lightening and enhancing the flexibility of the working pad and providing alternate hard and soft spots in the outer surfaces thereof.

' HARRY W. DEMPBEY. 

